The studies described in the following proposal will be performed to approach an understanding of gene depression in tumor cells which is manifest in the ectopic expression of various proteins. In particular, the regulation of synthesis of the alpha subunit of the glycoprotein hormones by HeLa cells will be examined. The experimental approach will include three broad areas: 1) Tissue culture will be employed to examine alpha subunit production in various HeLa lines and to evaluate the effects on alpha subunit synthesis of metabolites and metabolic analogs which have been shown to alter the synthesis of a variety of proteins in several tumor lines. 2) Because differences in the ectopic and normal molecules may provide some insight into their mechanism of synthesis, the HeLa alpha protein will be purified and its structure compared to that of human chorionic gonadotropin. 3) The cell-free synthesis of alpha will be used to purify its corresponding mRNA. Hybridization studies with alpha cDNA will directly examine the regulation of alpha synthesis by measuring alpha mRNA and DNA sequences in various HeLa lines and under various culture conditions.